It is known in the prior art to cause ozone to act on unsaturated fatty acids such as oleic acid, thereby effecting continuous ozonization of their double bond (Japanese Patent Publication No. 4714/1961 or U.S. Pat. No. 2,813,113 and Japanese Patent Publication No. 9206/1968).
The prior art continuous ozonization methods of unsaturated fatty acids which use an apparatus having a plurality of reaction zones and rely on the counterflow gas-liquid contact process of contacting unsaturated fatty acid solution with ozone-containing gas in a counterflow manner, however, are dangerous because excess ozone can be locally supplied to form peroxides. The counterflow gas-liquid contact process of this type is difficult to quickly remove reaction heat from the apparatus or reactor tower.
German Patent No. 2,713,863 discloses a method for continuously producing an ozonide (or ozonized product) by ozonizing a high molecular weight olefin, oleic acid or linoleic acid in the presence of water and an organic acid or alcohol. Since this method supplies the reactant and an ozone-containing gas in parallel flow relationship, but does not form a thin film flow of the reactant, it is necessary to efficiently remove reaction heat generated during ozonization and to add large amounts of water and organic acid or alcohol for keeping the resulting ozonide (or ozonized product) stable, thus resulting in low yields per unit time. Moreover, although a plurality of static mixers are provided in the reactor tower for mixing organic acid and water, it is difficult to maintain a stable emulsion. As emulsion particles become larger, local heating occurs inevitably.
Also known in the prior art is oxidative decomposition by causing oxygen to act on ozonized products of unsaturated fatty acids (Japanese Patent Publication No. 4717/1961).
Although the oxidative decomposition reaction of ozonized products of unsaturated fatty acids is said to take place at a temperature of 75.degree. to 125.degree. C. according to the Publication, the actual temperature was limited up to 100.degree. C. Thus the oxidative decomposition reaction took a long time, resulting in low yields. If reaction were performed at high temperatures of 100.degree. C. or higher, especially 125.degree. C. or higher, abrupt oxidation would occur, imposing a safety problem. Also, part of the final product could be oxidized into carbon dioxide and water while forming by-products, leaving a problem in yields.
Therefore, there is a need for the development of a commercially advantageous method for the oxidative decomposition of ozonized products of unsaturated fatty acids.